Influência dos créditos de carbono na viabilidade financeira de três projetos florestais Influence of carbon credits on the financial viability of three forest projects

O presente trabalho teve como objetivo estudar a influência dos créditos de carbono na viabilidade financeira de três projetos florestais. Os projetos analisados foram: heveicultura, eucalipto e pinus para produção de borracha, celulose e resina, respectivamente. O Valor Presente Líquido (VPL), a Taxa Interna de Retorno (TIR), o Valor Esperado da Terra (VET) e o Valor Anual Equivalente (VAE) foram os indicadores utilizados na avaliação financeira, a uma taxa de desconto de 10% ao ano. Os resultados deste trabalho indicaram que, com esta taxa, os projetos de eucalipto e pinus foram viáveis sem os recursos adicionais dos CERs (Certificados de Emissões Reduzidas), ressaltando-se que a inclusão dos créditos de carbono propiciou aumento da viabilidade financeira destes. Já o projeto da heveicultura mostrou-se viável apenas com os Certificados de Carbono. A receita advinda da venda dos CERs aumentou consideravelmente a viabilidade financeira dos três projetos, mesmo considerando a tonelada de CO2 a US$3,00. Caso o Protocolo de Kyoto seja ratificado, haverá um incremento no preço pago pela tonelada de CO2, que ocasionará o aumento da contribuição dos CERs em projetos florestais.<br>The objective of the present work was to study the influence of carbon credits on the financial viability of three forest projects. The analyzed projects were: heveiculture, eucalyptus and pinus for production of natural rubber, cellulose and resin, respectively. The Net Present Value (NPV), the Internal Return Rate (IRR), the Soil Expected Value (SEV) and the Equivalent Annual Value (EAV) were the indicators used in the financial evaluation, using a discount rate of 10$3,00. In case of ratification of the Kyoto Protocol, there will be an increment in the price paid for ton of CO2, which in turn will increase the contribution of CERs in forest projects

Nitrogen balance in soil under eucalyptus plantations

An understanding of the role of organic nitrogen (N) pools in the N supply of eucalyptus plantations is essential for the development of strategies that maximize the efficient use of N for this crop. This study aimed to evaluate the distribution of organic N pools in different compartments of the soil-plant system and their contributions to the N supply in eucalyptus plantations at different ages (1, 3, 5, and 13 years). Three models were used to estimate the contributions of organic pools: Model I considered N pools contained in the litterfall, N pools in the soil microbial biomass and available soil N (mineral N); Model II considered the N pools in the soil, potentially mineralizable N and the export of N through wood harvesting; and Model III (N balance) was defined as the difference between the initial soil N pool (0-10 cm) and the export of N, taking the application of N fertilizer into account. Model I showed that N pools could supply 27 - 70 % of the N demands of eucalyptus trees at different ages. Model II suggested that the soil N pool may be sufficient for 4 - 5 rotations of 5 years. According to the N balance, these N pools would be sufficient to meet the N demands of eucalyptus for more than 15 rotations of 5 years. The organic pools contribute with different levels of N and together are sufficient to meet the N demands of eucalyptus for several rotations